The difference between dot (a.k.a. full stop, period) and comma in Perl
If (Perl) I write
$x = "12";
$y = "25";
print $x,$y;
print $x.$y;
print "\n";
Then I'll get output
12251225
In other words - the output is the same. So is there a difference?
Yes - there's a huge difference.
$x.$y
- using the dot operator - joins the two strings together (concatenates them) into one.
$x,$y
- using the comma - passes the two strings forward as a list so they are printed one after another.
You can see the difference if you write
@abc = sort($y,$x);
@def = sort($y.$x);
In the first case, using , (comma), @abc is a list that's two sorted elements long, so it's
['12','25']
whereas in the second case, using . (full stop / period), @def is a list of one item, nothing to sort, so it's
['2512']
Full example, including output,
[here] from this week's
Perl Programming Training Course.
(written 2011-12-09, updated 2011-12-17)
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